In the past there have been problems associated with catheters used for delivery of fluids from drug delivery apparatuses. The problems were ones of maintaining the sterility of the catheter when being inserted in the human user and all necessary connections were being made to the drug delivery apparatus. There were also problems in effectively priming the conduit line from the drug delivery apparatus to the catheter and the catheter itself. Further, when there was a need for a prolonged period of drug delivery, the use of catheters was considered not feasible. With the introduction of flexible catheters there has been some renewed interests in their use for drug delivery systems but the other problems still existed.
Even though the advent of flexible catheters has provided an easy method for drug delivery, there was still a great deal of continued use of surgical insertions for human users who must use a drug delivery system over a long period of time. The continued use of surgical implantations was based primarily on the fact that it can be surgically implanted underneath the skin and the user would not have to worry particularly about it coming out.
The use of non-flexible and flexible catheters has always had the problem of unintentional removal by the human user due to some type of accident. Once this has taken place, then there is a continued problem of what to do to replace the catheter.
When there was a rigid tip catheter, it was very simple, catheter could be resterilized with a sterilizing fluid such as alcohol and it could then be reinserted intravenously or subcutaneously and fluid delivery could be continued as before. When flexible catheters were used, it was not as easy. Flexible catheters could not be reinserted because the flexible tip is blunt and cannot independently pierce the skin. Therefore, the catheter that had been removed from intervenous or subcutaneous insertion could not be reinserted. In such case, a new catheter has to be obtained and reinserted. It takes more than one person to carry out such catheter insertion and surely it would be difficult for a patient to carry these activities yet alone.
The prior art discloses flexible catheters. The Angiocath by Deseret is such a catheter and has a "Y" shape. The flexible catheter by Deseret has a retractable type needle within the confines of the flexible tip of the catheter which is used primarily for insertion into the human user. Once insertion is made the needle is removed and the delivery system is allowed to pump according to the delivery schedule for the individual user. However, there was quite a bit of problems with priming the system and determining when a vein has been properly pierced for fluid delivery to the human user.
In this type of catheter the hub of the needle has thereon disposed a porous end which will allow air to pass through but not liquid. Therefore, when a vein is pierced the blood will travel up the needle core to the hub. The air will be forced out of the porous needle hub but the blood will not pass through it . However, once the blood contacts the porous hub membrane, it clogs it and prevents it from further effective use. Therefore, if positioning was not precisely correct and it had to be repositioned it would be difficult to determine if position was correct because the system could not be purged and reused since the porous membrane was clogged.
In an attempt to make the process easier Deseret constructed a viewing chamber which is referred to as an "extension" which is used to view the blood after it passes through the needle core and into the hub prior to contacting the porous membrane. This attempts to provide an effective means to determine if the insertion is correct, but the same problems with the membrane existed. It could be clogged and rendered ineffective once contacted by blood. Additionally, this catheter had not solved the priming problem which existed for effectively and easily priming the catheter and line from the delivery apparatus.
Referring to the priming technique that existed for apparatuses as shown by Deseret, in order to properly prime the catheter, the needle tip of the flexible catheter must be inserted into the vein of the human user or subcutaneously. After the insertion, blood is allowed to back up through the core of the needle and allowed to trickle out of the back end of the needle hub indicating a proper intervenous insertion. Once this is carried out, there is priming of the system by retraction of the needle to the central body of the catheter to allow blood to back up through the Y section of the body to indicate that the catheter is primed with blood. Priming could not be carried out in body of the catheter with the fluid for the human user because like air in the body would be forced in the vein or subcutaneous insertion point of the flexible tip once the needle was removed to allow such priming.
This method is utilized by many. However, is very inefficient and there can be some sterility problems in carrying out the Priming method as described for prior art type flexible catheters. The sterility problems associated with priming are centered around opening the system to prime it and reconnecting the system. During these activities the system is susceptible to contact contamination.
Such contamination in some cases could cause infection, sickness or could even be fatal for the individual.
These and other problems are solved by the present invention.